1. Field of the Invention
The present invention relates to hybrid printers that put two images on a single page, more specifically, this invention solves the print quality problem that results from misregistration of portions of the second print image on the first print image.
2. Description of the Prior Art
Hybrid printers print two images on a single page. A common type of hybrid printer combines laser and color ink-jet printing on a single page. In this type of printer, the laser print engine will print the black image on the page and then feed the paper into a color printer, such as an ink-jet, where the color (CMY) part of the image will be printed. The largest print quality issue that results from this process is the lack of uniform registration between the black and color portions of the image. Whenever the black plane of an image is stretched or compressed in the horizontal or vertical direction, the color planes that are subsequently printed will appear misregistered.
Distortion in the black plane image is inherent in some print processes and may not vary between printers of the same model. The distortion measured for such printers will stay the same throughout the life of the printer. Many factors cause black plane distortion in the laser printing process such as heat, variations of speed of the paper, humidity, and optical characteristics of the laser system Distortion may be in both the horizontal and vertical directions, may be linear or non-linear, and could be in both processes. If the distortion is identified and measured it becomes predictable and may be masked or camouflaged.
The human eye cannot detect the distortions that exist in the laser process when only the black and white image is printed. However when another undistorted or differently distorted image, such as a color image, is printed on top of the black and white image, distortions of the black plane image become apparent. Thus, it is therefore not cost effective to correct the distortions of the laser printer in hardware. This invention addresses the need for masking or camouflaging distortions of the black plane image without hardware.